This invention relates to an apparatus for automatically inserting transparencies into one-piece frames.
Known diapositives comprise a transparency obtained generally from film, and a square frame of standardised outer dimensions provided with a window for the transparency. Each frame, which for special requirements can be of cardboard, but is normally of plastics construction, is formed from two half frames which are joined together to retain the interposed transparency.
A known type of frame for diapositives comprises two half frames joined together along three sides and free along the fourth side, to thus form a type of "envelope". Suitable apparatus resiliently separates the facing sides of the two half frames by 1 or 2 mm, and inserts the transparency through the aperture formed in this manner. This insertion, which is obviously only partial, is completed by a suitable gripper which then grips the transparency through the window of the two half frames and drags it until it is centered with respect to them.
A drawback of this known type of frame is that the smallness of the insertion aperture can cause slippage of the transparency, which is not always prefectly flat but is often slightly curved. A further drawback is that the gripper which completes the insertion and centering of the transparency between the two half frames operates against the surface of the transparency and can damage it.
Another known type of transparency frame comprises two separate half frames, of which one is provided with adhesive points to which the transparency is made to adhere. The second half frame is then joined to the first by snap-insertion.
A drawback of this design is that the transparency remains permanently soiled by the adhesive and can no longer be used for other processes (duplication, printing etc.) for which it would have to be removed from the frame. A further drawback is that the existence of two separate pieces (half frames) results in increased difficulty in joining them together.
A frame is also known formed from two half frames which are hinged together along an adjacent side and can be "closed" in order to retain the interposed transparency. The apparatus which automatically effects this insertion is provided with suckers which retain the transparency as the half frames are folded over and snapped together. A drawback of this design is that the transparency is touched by the suckers on insertion, and can therefore be damaged.